Hi everyone. While looking through BioOne, I
chanced upon a review of Chiappe et al.'s Confuciusornithidae monograph written
by Storrs Olson. I was kindly given a copy of Chiappe et al. by coauthor
Mark Norell and I find many of Olson's critiques unfair and biased, which is why
I'm writing this defense.
"The authors,
steeped in cladistic fundamentalism, have been among the more insistent
proponents of the origin of birds from theropod dinosaurs, with its attendant
corollaries, such as the origin of flight from the ground
up."
Here again, we see the common misconception that if
birds are dinosaurs, flight must have evolved from the ground. This
ignores the possibility of small arboreal theropods, realized in recent years
with the discovery of Rahonavis and Microraptor.
"It has also been suggested that the otherwise inexplicable proximal
humeral foramen of Confuciusornis is an artifact. Although Chiappe et al.
deny this, information in their paper may be interpreted to the contrary, so to
this reviewer the issue remains unresolved."
Chiappe et al. state "...many of the specimens
studied here have been carefully prepared, and there is little doubt this
foramen was a true feature of Confuciusornis sanctus." and, "Of these, specimens
.....(specimen numbers)...... were fully prepared at the American Museum of
Natural History and are the nucleus of this study." If the AMNH can't
prepare a specimen accurately, who can? I see nothing in Chiappe et al.
that could be interpreted as supporting an unnatural origin for the humeral
foramen and no reason to doubt its existance.
"Instead of summarizing this literature, however, Chiappe et al. have
selectively chosen from it various points of which to be critical, even when the
view in question may not be the most current. Such selectivity, apart from being
disingenuous, detracts from the usefulness of the work as a whole, which cannot
be relied upon to supercede the earlier literature. For example, Hou et al.
(1999) are cited only to say that Chiappe et al. were “unable to examine the
recently described Confuciusornis dui. Yet, nowhere is it mentioned that
the main importance of this specimen is that it preserves the horny
rhamphotheca."
I know of nothing in Chiappe et al. which conflicts
with recent work, when that work is correct. Olson's example is not valid,
as the main importance of C. dui was to establish confuciusornithids had a
complete diapsid temporal arrangement. Chiappe et al. discuss the presumed
presence of a horny rhampotheca (pg. 18, 50). While I would have enjoyed
discussion of C. dui, the species was described the year Chiappe et al. was
published.
"Food processing by a toothless bird with an akinetic skull would be highly
problematic, so a more detailed study of the wealth of specimens potentially
available will more likely show that the skull was in fact kinetic."
This is highly unlikely due to several features
Chiappe et al. describe (premaxillae firmly attached to frontals; jugal high
anteriorly; jugal-postorbital suture; quadratojugal-squamosal suture; jugal
anchored to palatine by ectopterygoid?).
"They illustrate (figure 34) what they claim to be uncinate processes
articulating with six ribs in only a single specimen of Confuciusornis,
from which they go on to speculate “that their absence in other basal birds 
may be due to preservational factors or ontogenetic development” (pp.
32–33). This goes beyond special pleading, because the authors could not
possibly believe that this would explain the absence of uncinate processes in
all of the specimens of Archaeopteryx or in any of the hundreds of other
specimens of Confuciusornis."
may be due to preservational factors or ontogenetic development” (pp.
32–33). This goes beyond special pleading, because the authors could not
possibly believe that this would explain the absence of uncinate processes in
all of the specimens of Archaeopteryx or in any of the hundreds of other
specimens of Confuciusornis."Olson obviously didn't read the paper clearly
enough, as the authors clearly state "Remnants of uncinate processes or their
caudodorsally oriented molds are also visible in several other specimens (eg.,
GMV-2130, GMV-2146, and GMV-2147)." In fact, these can be seen in figure
28 (GMV-2130) and figure 31 (GMV-2147).
Regarding the statement preservational factors
could not be responsible, I wrote the following a while back-
How many dromaeosaurid specimens have uncinate
processes preserved? One (the fighting specimen of Velociraptor).
And how many oviraptorid specimens? Two (IGM 100/979 and IGM
199/1002). It may seem there are a ton of enantiornithine
specimens out there with obviously absent uncinates, but despite the number of
named species, very few good specimens exist. Most well-preserved
enantiornithines (Concornis, Eoalulavis, Spanish nestling, Sinornis,
Cathayornis, Neuquenornis, Boluochia, Longchengornis, Cathayornis? caudatus,
Cuspirostrisornis, Largirostrornis) have only a few scattered ribs preserved at
most (or are broken in that area, like Sinornis) and often preserve small
structures that could easily be uncinates, although they could just as easily be
sternal ribs or dorsal rib fragments. The same is true of Changchengornis,
which preserves two fragments that may be uncinates, but might not be as
well. The only specimen you might be able to make a case for is
Iberomesornis, which has an articulated ribcage on its left side. This
specimen is clearly juvenile however, due to the unfused metatarsus and sacrum,
etc., which could be a plausible reason for the apparant lack of ossified
uncinates.
"One aspect of
its wrist must have been as well developed as in modern birds, however, as
inadvertently demonstrated in figure 70, which shows a reconstructed skeleton of
Confuciusornis with the shaded outline of the body and wings. Here the
hand is shown extending down at an angle of about 45° from the horizontal. In
this position, had the bird been terrestrial, as the authors would prefer, its
long primaries would have been pressed down and bent against the surface of the
ground. Instead, the primaries are shown projecting straight back, horizontally,
as though they were coming off the ulna perhaps."
Untrue. Tracing the primaries back to the
forelimb clearly shows they would have attached to the manus in figure
70.
"The pelvis has
the avian retropubic construction, ..."
Just a question: Is the term "retropubic" used in
relation to bird pelves? I always thought it was opisthopubic. A
Google search for retropubic only brings up medical references. It looks
to me like an attempt to make birds seem less dinosaurian....
"That Changchengornis is a valid genus is highly doubtful. ... What
is apparent is that it has the same wing shape, the same two elongated
rectrices, the same distinctive shape of the humerus, and the same overall
proportions of the wing and leg as Confuciusornis."
Chiappe et al. find twelve differences between the
genera. These are not variable within Confuciusornis specimens and appear
valid. The many similarities simply support placing the two in the same
family, as Chiappe et al. have done.
"At one point (p. 67), Chiappe et al. say of Changchengornis that
“the phalangeal formula of the foot is typical of theropod dinosaurs: 2-3-4-5-x
” Who do they expect to impress with this choice tidbit? It happens to
be true, but it is also true that the same phalangeal formula is found in
Confuciusornis (p. 47) and is the typical and primitive condition found
in almost all birds. Such gratuitous statements are characteristic of the
propagandizing that the theropod proponents of avian origin seem to think is
necessary to bolster their hypothesis."
” Who do they expect to impress with this choice tidbit? It happens to
be true, but it is also true that the same phalangeal formula is found in
Confuciusornis (p. 47) and is the typical and primitive condition found
in almost all birds. Such gratuitous statements are characteristic of the
propagandizing that the theropod proponents of avian origin seem to think is
necessary to bolster their hypothesis."A might harsh, don't you think? Perhaps Olson is
annoyed at the 2-3-3-3-3 formula of Megalancosaurus or the 2-3-4-5-2
formula of Cosesaurus. ;-)
"In the same vein, Chiappe et al. refer to the digits of the hand in the
Confuciusornithidae with the theropodan formula of I, II, III, whereas it has
been repeatedly shown (Holmgren 1955, Hinchliffe 1985, Burke and Feduccia, 1997)
and conceded (Wagner and Gauthier 1999) that the digits of the hand in birds are
II, III, IV. Because this is such compelling evidence against the theropod
origin of birds, it is hardly any wonder that Chiappe et al. cannot bring
themselves to use the correct formula."
Or perhaps good genetic evidence shows frameshafts
can occur and change which digits appear to be developed.... Just because
the digits of neornithines are 2-3-4 doesn't mean they always were.
In all fairness, Olson does mention some actual
problems with the paper (lack of behavioral analysis or biomechanical
considerations, few reconstructions and measurement tables), but the positives
far outweigh the negatives.
"Thus, if Chiappe et al. actually understand the true significance of
Confuciusornis, then they have done their best to prevent it from being
revealed. Their paper will stand as an exemplar of manipulation of information
to conform to preconceived ideas, but it is otherwise insufficiently credible or
comprehensive to constitute a lasting addition to knowledge."
Ouch. I completely disagree. This
monograph is the best available for a non-ornithurine pygostylian. A very
detailed description compliments extensive photographs. Such a document is
sorely needed in a time when complete basal pygostylians are mentioned briefly
in Science/Nature or described in Chinese.
Olson's review can be read here-
Mickey Mortimer